Thirty minutes a day on the piano for our children, ages 7 to 10, but they aren't going to Carnegie Hall on that schedule. Sometimes they play just for the fun of it, which is a reason to continue their lessons. If they only ever played out of compulsion we ought to stop.
This is the schedule we've agreed to with our DD14, as well-- she's done things this way for years, and sometimes fights it, and sometimes not, and we're not terribly rigid about it during a week when things go topsy turvy.
At the late intermediate level, understand, this means working on a piece for
months at a time. Our DD is quite talented, but she doesn't really
value this talent very highly, nor have intrinsic motivation to excel at piano-- I mention that only to note that this amount of practice time is WHOLLY inadequate for most piano students at this level-- even pretty talented ones. DD doesn't seem to need a lot of repetition to improve. PLAYING time counts more than repetition of what she's working on. Can't really explain that one, but it seems to be true.
